The molding of foam rubber has been known for considerable time. Non foamed articles may be made by slush molding or rotational molding. In these processes a mold is at least partly filled with an aqueous dispersion of a polymer. The mold is rotated to cover the inside surface of the mold with the dispersion. The internal mold surface corresponds to the external surface of the rubber part. Dip molding is also known. In dip molding a mold is dipped into a bath of an aqueous dispersion of a polymer. The polymeric dispersion is caused to coagulate on the mold. The resulting product may then be turned inside out, as in rubber gloves, so the external texture and detail on the mold corresponds to the external surface of the rubber part. These molding procedures have not been widely used with foamed dispersions or latices other than the manufacture of children's toys. In such processes each article is individually molded and the article is not cut.
There is considerable art pertaining to the molding of slabs or blocks of foam. Foam slabs may be made in a fixed mold such as in the Talalay process described in Canadian Patent 591,979 issued Feb. 2, 1960 to B. F. Goodrich. Generally, the process requires a high amount of cooling. The mold is expensive.
British Patent 450,920 issued Jan 22, 1935 to International Latex discloses the continuous production of long lengths of rubber. The rubber is molded in an open ended mold composed of a plurality of endless moving surfaces such as belts. Such a mold is expensive.
Gel foams are also known. These foams may be prepared by heating foamed aqueous dispersions of polymers in molds or spreading it as relatively thin sheets on substrates such as carpet backing.
In the current production of small shaped foamed articles the foam is prepared as a slab. The slab is split to the correct thickness and then cut to the required shape. This process is used to make cosmetic puffs. There is a large amount of waste in the process and it is relatively labour intensive.
Applicant has not been able to locate any description of a simple inexpensive process for producing a shaped foam rubber which may then simply be cut to the desired length. The present invention seeks to provide such a process.